


What Are Sisters For?

by Anonymous



Category: The Umbrella Academy (TV)
Genre: Ambiguous Relationships, Crying, Diapers, Gen, Littles Are Known, Non-Sexual, Non-Sexual Age Play, Other Additional Tags to Be Added, Thumb-sucking, Wetting, like diego/klaus is alluded to but it’s more platonic than anything
Language: English
Status: In-Progress
Published: 2019-05-10
Updated: 2019-05-10
Packaged: 2020-02-29 14:23:15
Rating: Not Rated
Warnings: No Archive Warnings Apply
Chapters: 2
Words: 4,254
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/18780058
Author URL: https://archiveofourown.org/
Summary: Vanya is a neutral. Klaus is a little.What happens when Klaus wakes up, sobbing and littler than he’s ever been in his life, with no one else home but Vanya?orThe adventures of Caregiver!Allison, Neutral!Vanya, Little!Klaus, and Little!Five





	1. Chapter 1

**Author's Note:**

> I DON’T SEE ENOUGH OF SISTER/BROTHER BONDING IN TUA NSAP FICS SO IM WRITING THIS FOR MYSELF SKDHSIXBK.

Klaus woke to the sun shining through his blinds, warm slits of light settling on his face and chest like an indirect hug. It soothed him as he arrived back into reality, having been dead to the world for well over eight hours by that point. The deep, uninterrupted sleep surprised him, really. He made it through the night without a nightmare, and without waking up, not even once. It felt nice.

But, as he rubbed the sleep from his eyes with balled fists, he started to realize that he wasn’t feeling all too well mentally. His mind felt as if it had a light haze surrounding it, like he needed assistance to do the simplest of things such as get out of bed. He wasn’t an idiot, he knew his mind and his body well enough to know that he was waking up in headspace. A very, very deep headspace that he hadn’t quite realized the extent of yet.

“Di..” He mumbled, voice deep and hoarse as a side effect of sleep. Silence. Klaus’s brows creased, and he threw his arm to the other side of the bed, patting it lazily. Empty. No Diego. No one to help him get up, get dressed, eat, and make him feel safe. Holy fuck, he wanted to cry _immediately._ “Di, Di. Diego-o.” He struggled with pronunciation, showing just how far he was regressing. He couldn’t be more than a year old, and he just didn’t know what to do. He’d never been this far regressed before, and it scared him. His small mind couldn’t comprehend the fact that Diego wasn’t around, and that he was alone in his room, by himself, with no one to help.

He started to sob.

It started slow, naturally, his eyes tearing up and a lump settling in his throat, but soon enough it turned into tears streaming down his reddened cheeks, and him wailing as if he was being brutally tortured. His tears didn’t slow, and he found himself struggling and hiccuping as he tried to breathe, his legs kicking frantically against the bed and his fingers gripping the sheets for dear life. He needed someone to hear, he couldn’t be by himself, he couldn’t do it, he—

“Klaus? Klaus, buddy, I need you to listen to my voice for me.” Klaus hadn’t even heard the door open, unaware of anyone’s presence until they’d spoke. They were petting his hair gently, and he still didn’t know who it was because he’d been so busy with his hysterics. He looked beside him, more tears coming to his eyes as he released another heart wrenching sob, reaching for his sister and grabbing frantically.

“Va..! Va-anya!” He hiccuped, clearly struggling. He managed to grip her sleeve tightly, tugging at it as he took wet, shallow breaths accompanied by little whines and sobs. She continued to pet his hair, shushing him in almost a rhythmic pattern until his sobs died down into small, pitiful cries.

“There we go. You’re okay. I’m right here.” She assured, and he grabbed more urgently at her, craving more physical contact. She picked up on it, climbing onto the bed and cradling his head against her chest as his hands fisted at her sweater.

“Va, Va..” He cried quietly, like he wanted something but didn’t know how to ask. He was still clearly distraught, meaning something else wasn’t right and he needed something, or perhaps it was multiple things, considering he’d only just woken up. 

“What is it?” Vanya asked, looking down at him. Honestly, she was completely winging this. She was a Neutral, so she usually never took care of Klaus’s main needs when he dropped, she mostly watched him for short periods of time, or other small responsibilities like that. No one else was home at that moment, though, so she’d been the only one to react when she’d heard Klaus’s hysterical crying.

“Hung’y.” He managed, the word barely above a whisper. He still clung tightly to Vanya, like if he let go she’d disappear into thin air and he’d be all alone again. Naturally he was hungry, he hadn’t eaten since dinner the evening before, and Vanya remembers him, in all the glory of his 6 year old headspace, conking out on the couch at 7pm and Diego carrying him up to his bed. She was sure no one in the house expected him to wake up like this, which was why the house was empty, at the moment. Allison was food shopping with Five, who was also regressed into his usual 3 year old headspace, and Vanya was still unsure about how she was going to get anything effectively done with a toddler on her heels; though she supposed Caregivers were just naturally that good at managing.

She wasn’t entirely sure where Diego was, but he said he’d be back by 11am at the very latest, so she glanced at the clock, groaning near audibly when it read only 9am. And with Luther not even being in the country, she didn’t know how long she was going to be looking after Klaus. A very, very young Klaus, which didn’t make it any better. And it wasn’t that she didn’t want to— no, that had never been it, she loved her little brother so much, but she just didn’t feel capable. At least not as capable as Allison and Diego, who were Caregivers, and who had the help of their own biology.

“Okay, let’s go downstairs and I’ll make you some food. Or mom can, whichever comes first.” She slightly rambled, and Klaus didn’t seem to mind her over abundance of words, in fact, it almost looked like he was comforted by it. She nudged Klaus slightly, and he sat up, curls sticking up in a wild bedhead that prompted a breathy chuckle from Vanya. Klaus rubbed his eyes with lazy, sleepy movements as Vanya helped him stand, and he wobbled on his feet, damn near falling over if Vanya hadn’t gripped his waist and steadied him. She knew he needed to be carried, that he was so small and walking was such a large feat for him, but she wasn’t strong enough, nor was she tall enough, so keeping him steady while they made their way slowly down the stairs was about all she could do.

She sat Klaus at the kitchen table, and he gave something like a delighted hum, one of his hands finding purchase on the edge of the table while the other was rooted in his mouth, him chewing on his pointer and middle fingers in the absence of a pacifier. Vanya knew better than to let him do that, but she decided to leave it for the time being, since she was unsure where the pacifiers were and Klaus didn’t seem like he could function without the comfort.

Vanya rummaged through the kitchen cabinets, the fridge, the freezer— there wasn’t much, which was why Allison was currently at the store, but she had found a jar of baby food in the back of the pantry that wasn’t expired, thank god, and grabbed a spoon from the drawer, promptly sitting across from Klaus in preparation to feed him, not trusting him keep himself, and everything around him, clean in the process of feeding himself. The food was banana mush, basically. Klaus liked bananas. It should be okay, she thought.

Klaus whined, bouncing slightly in his seat in what Vanya deduced as restlessness, so she shushed him, raising a spoonful of the food near Klaus’s mouth. His lips stayed firmly shut, and he shifted again, his brows drawn firmly together in an upset expression. 

Vanya was confused. Really, she was confused, and she didn’t know how to take cues from Littles. She’s was so out of her depth in so many ways, and she was just trying to manage until Allison or Diego got back. “You just said you were hungry. Here’s food!” She said, trying her best to act enthusiastic so that maybe Klaus might as a result. He stayed with his upset expression, and Vanya thought maybe he was just being defiant. It wouldn’t be the first time.

Well, she did think that, but then Klaus’s expression changed into something a little more lax, but his cheeks got red and his eyes started to gloss up with unshed tears. She was confused, once again, until she heard dripping. Right in front of her. Liquid onto the hard tile of the kitchen floor. She got up fast, leaning over the table to examine Klaus and confirm her fear and suspicion, dread and that incapable feeling once again settling in the pit of her stomach.

Klaus’s pajama pants had gone from light to dark gray in a large stain going down his legs, a puddle quickly forming beneath his chair. He’d gone to bed in a much older headspace, meaning he hadn’t even had a pull-up on, much less a diaper, which she was now sure he was going to need in such an obviously deep headspace. She felt like an idiot, and now Klaus was working himself up again, his breathing getting rapid and tears rolling down his cheeks in rapid succession. And then the sobbing was back, the tortured wails that would make any Caregiver immediately rush to the source.

It was all an absolute mess, and Vanya wasn’t really sure how to fix it.

Which was why she wanted to give her sister the biggest hug when she came through the door, grocery bags in hand and little Five running in ahead of her.


	2. Chapter 2

**Notes for the Chapter:**

> hey!!! sorry for not updating in so long! i’ve been busy, but i’m gonna promise more regular updates at this point! thanks for your patience!

Allison could really only describe it as chaos when she walked through the door. Pure, unadulterated chaos, and suddenly she couldn’t pick apart what were Klaus’s distressed wails and what were Five’s joyous squeals as he ran on pure sugar and toddler energy. _’I really shouldn’t have bought him that ice cream.’_ She thought between the frantic rush of hormones to her brain at the distraught sound of Klaus, and Vanya, the bundle of anxiety she was, poor thing, trying her best to explain the situation.

“Klaus is- Oh Christ, I’m sorry, I tried, but I’m just not like you or Diego, and he’s just so small right now I didn’t even think about it until he just- Well, he just—“ Vanya’s word vomit was really the last thing Allison needed, because she wasn’t sure she could stop from comforting Klaus for another second, so she cut her off, kind and gently as she could muster.

“I’m sure you did great, okay? I’ll take care of Klaus, just please make sure Five doesn’t get into anything he shouldn’t.” Allison said, dropping the grocery bags carelessly on the counter and breezing past Vanya so she could soothe their incredibly little brother. Vanya stood, a little dumbfounded and still buzzing with anxious energy, before obeying her sister’s request and finding Five in the living room. 

Five’s eyes lit up at the sight of Vanya, bright and childlike and absolutely filled to the brim with joy. If Vanya didn’t know any better, she’d think he’d just done a line of coke. But, no, that was just Five sometimes. Only when he was little, of course. Usually, he was chilled out, well behaved, and clingy in headspace, but sometimes he just got a little.. hyped. Especially if he had any sweets, which he wasn’t particularly fond of anyway, so it was indefinitely rare. Of course it was now, Vanya thought, when Klaus was still in distress one room over despite Allison’s obvious efforts.

“Sissy!” He said, and Vanya could have sworn she could see him visibly buzzing with the amount of energy that was bouncing around in his sixteen year old body. He ran over and hugged her, resting his head on her shoulder and grabbing fistfuls of the back of her sweater. Oh, Five loved Vanya. He loved her so much, and in the deepest of headspaces he’d even admitted how much he wished she was a Caregiver so she could take care of him like Allison and Diego did.

“Hi, bud. Did you have fun with Allison?” She asked, smile audible in her voice as she hugged him back. He seemed to light up once more at the mention of the trip, pulling away from the embrace and going to grab something off the coffee table. God, she was exhausted just watching him. Usually this kind of behavior was more of a six year old Klaus thing, not a three year old Five.

“Got a new toy.” He said proudly, holding up a brand new stuffed puppy. It had big, cute plastic eyes and looked incredibly soft.

“I like it!” Vanya smiled, making Five absolutely beam in return. He tucked the puppy into the crook of his arm before slipping his thumb into his mouth. Vanya grimaced just slightly.

“You know Allison doesn’t like you to put your fingers in your mouth.” She said, and it had no real authority behind it, so Five didn’t obey. He just sort of looked at her, then at his feet, his thumb never leaving his mouth. 

“Sissy do a puzzle with me?” He asked hopefully, words muffled by his thumb, completely dropping the previous subject. Vanya sighed a tiny bit at his disobedience, but nodded, going over to the shelves and grabbing a kiddie puzzle, setting it out on the coffee table for her and Five to do.

•~*~*~•

Allison was sure she’d never seen Klaus so far regressed before, not since they were assigned their classifications. Very late in life, might she add, due to their father’s unwillingness to accept the fact that some of his children were going to be Littles. The odds of all seven of them being either Neutrals or Caregivers was pretty impossible, but even Allison wished that it was, because the amount of shit Klaus and Five got for being ‘inferior’ was more than she ever thought they deserved.

“Hey, Klaus, sweetheart,” She started to soothe him, voice sweet like honey as she ran a gentle hand through his hair, “It’s okay. You’re okay.” She wiped some of the tears from his cheeks, only for them to be replaced by new ones seconds later. 

“N-No..!” He wailed, acquiring a grip on Allison’s sleeve. She continued to shush him and mutter certain nonsense, but he didn’t show any signs of calming down, which in of itself worried her. She just needed him to calm down enough so she could clean him up, because she was sure that sitting in cold, soggy clothes was making him more upset by the second.

“I’m gonna get you all cleaned up and taken care of, sweets. Then we can go sit with Vanya and Five, and we can all relax.” She told him, continuing the gentle motion of raking her hand through his curls. At the notion of getting cleaned up, his breathing began to even out. The tears were still coming, but they were silent, and Allison thought that was enough to move him upstairs and get him into a bath. “Okay, c’mon.” She said, lifting him up easily and settling him onto her hip, cringing slightly as the wetness from his pants immediately began seeping into her own clothes. Luckily, Klaus had always been light. He’d gained a little weight since getting sober, though, which Allison was actually thankful for. He didn’t perpetually look like skin and bones. He looked healthy.

Klaus laid his head on Allison’s shoulder as she carried him, his tears beginning to slow at the physical contact. He was down to wet, upset hiccups by the time Allison got him into the bathroom and set him on the toilet lid while she started to run a bath. He was still upset, though. He was scared that he felt so small, and he just wanted Diego, because Diego always knew what to do and how to make him feel better. He wanted to say that, but he could barely have the thought, much less communicate it.

“Arms up.” Allison said, and Klaus looked up a little bit, complying and letting her slip his pajama shirt over his head. She stood him up and stripped off his wet pants and briefs. Neither of them were phased by this, and they never had been. It wasn’t even inappropriate, really, because nudity wasn’t any kind of a vile concept when it came down to headspaces and classifications and everything else. 

Klaus was helped into the tub, and his muscles visibly relaxed as he sunk into the hot water, his tired eyes immediately closing as Allison started on shampooing his hair. His hands gripped the side of the tub loosely, his knees drawn up almost to his chin as his head lulled a little to the side. Allison gave a breathy chuckle at this, smiling fondly at how relaxed he seemed, finally. She washed the suds out of his curls with an old cup that sat by the tub, repeating this process with conditioner before grabbing a washcloth. “Sir forward a little, honey.” She requested, and he easily complied. She began to wash him, starting at his back and taking care as she moved on to other areas. 

“All done.” Allison murmured after rinsing the last of the body wash off of Klaus. She grabbed a colorful towel from under the sink, helping Klaus out of the tub. She dried off his hair a little vigorously, which made him giggle, before wrapping the towel around him and ushering him to Diego’s room, which was where most of his stuff was. Allison wasn’t sure how Klaus and Diego labeled their relationship, since it wasn’t something they were very open about, but she had heard Klaus have a slip of the tongue and call Diego ‘Daddy’ while in his headspace on a few occasions, making her suspect that something might be developing, whether it was platonic or otherwise.

“Can you sit here and be good for a few minutes while I go change my clothes?” She asked Klaus, who was now sitting on Diego’s bed, chewing on the edge of his towel with wide, innocent eyes. He looked hesitant, but nodded slowly. Allison wasn’t exactly comfortable leaving him there, but her clothes were stained with urine still from when she’d picked Klaus up earlier, and she wanted to get out of them. She pet his hair once before leaving the room, taking a couple minutes to change her clothes and throw her and Klaus’s dirty ones into the washer.

When she returned, Klaus was still sitting patiently, making a little smile appear on her face. “Good job.” She praised, although he hardly reacted. She went into the top drawer of the dresser, pulling out a diaper with a minimalistic star pattern and grabbing the baby powder that was on the nightstand. “Can you lay back for me?” She asked. He didn’t move, staring idly at the floor. She thought she saw his eyes well up with a bit of tears, but she couldn’t be sure. “Hey, hey, are you okay, sweetie?” She cooed, setting the items elsewhere on the bed and sitting next to him, her arm loosely around his shoulders.

“W-Wan’ Dada—“ His statement was wobbly, and seemed to almost die off at the end, as if he’d said something he wasn’t supposed to. “D-Diego.” He corrected, his tone thick with emotion that Allison wasn’t too sure he could control.

“He’ll be back a little later, okay?” She told him gently, rubbing his back. A few tears slid down his cheeks, and she shushed him before standing and pushing gently on his shoulders. He laid back without resistance, and she got to work diapering him, which didn’t take more than a minute. She tossed the wet towel into Diego’s hamper before going into the dresser and producing one of Diego’s favorite shirts. It wasn’t anything special, just plain gray, but she hoped having something of Diego’s on might soothe Klaus a little. “Arms up.” She said, and he complied once again, letting the shirt be slipped over his head. She decided to forgo pants, seeing as it’d be easier to keep an eye on the status of his diaper, and he might be more comfortable in general. He hiccuped quietly, fisting the fabric of the t-shirt before looking up at Allison and lifting his arms. She picked him up and settled him on her hip without hesitation, but he fussed.

“Puppy.” He whined. Puppy, ironically enough, was Klaus’s favorite stuffed kitten.

“Puppy’s downstairs, you left her there last night.” Allison told him, and he seemed to accept this, clinging to her shirt and laying his head on her shoulder.

Allison made her way down to the living room with Klaus in her arms, spotting Vanya and Five engrossed in a puzzle together. She sighed a little when she saw Five’s thumb rooted in his mouth— she was always careful to correct him about that, but it seemed as if Vanya had let it slide. “Hey guys.” She greeted, and the two others looked up with smiles.

“Doin’ puzzle.” Five said brightly, the words muffled by his thumb. 

“Sounds like fun.” Allison smiled as she entered the room fully, going into the diaper bag on the couch and getting out Five’s pacifier and teething toy. If it was one thing that Five loved when he was little, it was to chew on things, even if it was his own fingers (which she tried to avoid as much as possible). “Pick.” She told him, holding them out, and he happily picked the teether, beginning to chew on it rather than his thumb. At Allison’s shoulder, Klaus whined pitifully, making grabby hands at the pacifier that Five had neglected to choose, and she easily gave it to him, slipping it past his lips. He sighed a little, beginning to suck rhythmically on the soft plastic.

“P’ppy?” Klaus slurred behind the paci, his green eyes roaming around the living room trying to spot his favorite stuffie. Allison spotted it on one of the arm chairs, going over and picking it up. Klaus took it immediately, holding it to his chest tightly.

“He’s really young.” Vanya commented, and Allison gave a little nod, sitting down with Klaus, who cuddled up to her side. “How old do you think?”

“If I had to guess, probably six months to a year.” She answered, and Vanya hummed a little, turning back to the puzzle. Five was completely engrossed in it, his brows creased in concentration as he chewed his teether and tried piece after piece.

“I’m really sorry. Y’know, about not thinking. I just- no one was home, and I’ve never had to.. do that alone.” Vanya began to explain herself.

“V, there’s nothing to be sorry for.” Allison gave a kind smile, beginning to run her hand through Klaus’s curls when he fussed for no reason. “I get that you’re not a Caregiver, and it must have been really hard, especially with him this young.” She added, and Vanya smiled back, giving a slight nod.

Suddenly, the phone began to ring, startling all four of them and causing Klaus to squirm and tear up. Allison shushed him, and Vanya hopped up to answer it. “Hello?” She said.

“Hey, V, it’s Diego.”

“Oh, hey. What’s up?”

“Well, I know I said I was gonna be back today, but some things got a little complicated, and I might not be back for a few days.”

“Oh, is everything okay?”

“Yeah, just work. Is Klaus still regressed?”

“Definitely, yeah. Actually, he woke up in an infant headspace.”

“Shit. Does Allison have him?”

“Yeah, he’s okay, do you want to talk to him? I mean, he isn’t doing much talking, but..”

“No, no, that might upset him. He’ll already be upset about me being gone, just try to keep him distracted. I’ll be back in a couple days.”

And with that, Diego hung up, and Vanya hung the phone back up, making her way back into the living room. “That was Diego.” She said to the room, and she saw Klaus perk up. “He says he’s gonna be gone for a few days, but he’ll be back as soon as possible.” She added. Klaus’s pacifier dropped from his mouth and he began to whine, his eyes filling with tears in an instant as he fisted at Allison’s top.

“Wan’ Dada..!” He cried, his breathing coming in little gasps. He looked so small, clinging to Allison with his face so openly vulnerable. Allison gathered him up in her arms, rocking him slowly and trying to soothe him. Vanya sat back down with Five, who was watching Klaus with his arms crossed.

“What’s up?” Vanya asked. Five shifted uncomfortably, uncrossing his arms to fiddle with a puzzle piece.

“Nothing.” He murmured, although Vanya didn’t believe him.

“You can tell me, it’s okay.” She added. Allison had picked up Klaus and began pacing in the kitchen, bouncing him gently to stop his fit.

“Klaus gets to..” He started, his lips pursing as if he didn’t know how to say it. “He’s getting lotsa stuff I don’t get.” He finally said, pouting a little when he did.

“Like what?” Vanya prompted.

“Nothing.” Five closed himself off again, quickly as he opened up. This made Vanya sigh a little, but she didn’t push, and they both went back to the puzzle.

Looked like it was just going to be the four of them for a while.


End file.
